Problems in the allocation and persistence of attention occur in various psychological disorders (e.g., ADHD, autism, schizophrenia, and drug abuse). Attention appears to be in part a voluntary skill, but little is known about the role of differential consequences in the control of attention. Quantitative theories of voluntary (i.e., operant) behavior describe how differential consequences modulate the allocation and persistence of behavior, and may be applicable to attention. The matching law suggests that the allocation of behavior to two options equals the distribution of reinforcers obtained from the options. Behavioral momentum theory suggests that the persistence of behavior in the presence of a stimulus is governed by the rate of reinforcement obtained in that presence of that stimulus. This research aims to examine the applicability of these theories to the control of attention by differential consequences in an animal model. A procedure will be used in which pigeons are presented with samples comprised of two elements (color and line orientation) and then required to chose one of the elements from two element comparison stimuli (two colors or lines). Accurate performance requires the division of attention between the two elements of the sample. Change in accuracy will be used to measure the allocation and persistence of attending to each of the elements in the compound sample. The specific aims of this research are: 1) to determine if the allocation of attention to an element of a compound stimulus varies as a function of the relative distribution of reinforcement for attending to that element. 2) To examine the effects of differential reinforcement on the persistence of attending in the face of disruption. 3) To begin an analysis of the mechanisms through which differential reinforcement affects divided attention performance. The development of quantitative theories describing the role of differential consequences in the control of attention may lead to more effective behavioral interventions for disorders associated with problems in the allocation and persistence of attention. [unreadable] [unreadable]